JPH09288206A - Production of diffraction optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an optical element with good productivity by allowing a polymerizable liquid crystal compd. in a liquid crystal state to have such an oriented state that regions having different optical anisotropy from adjacent regions are mixed. SOLUTION: The diffraction optical element is produced by forming such an oriented state of a polymerizable liquid crystal compd. in a liquid crystal state that regions having different optical anisotropy from adjacent regions are mixed and then polymerizing and hardening the liquid crystal compd. As for the functional groups of the polymerizable liquid crystal compd., any groups which cause polymn. reaction such as epoxy groups, acrylate groups and methacrylate groups can be used. As for the polymerizing and hardening method, photopolymerization is preferably used. As for the method to produce the oriented state with the mixture of regions having different optical anisotropy for adjacent regions, it is preferable to hold a polymerizable liquid crystal compd. 6 between a pair of conductive substrates at least one of which is finely processed, namely glass substrates 1 having a stripe ITO electrode 2 and a solid electrode 3, and then to apply voltage on the substrates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a diffractive optical element used in a display device, a polarizing element, an optical lens, an optical computer, optical communication, an optical recording pickup, an optical recording material, or the like.

[0002]

2. Description of the Related Art Diffractive optical elements have come to be partially used or actively studied in display devices, optical recording pickups, optical interconnections and the like.
A device in which the surface shape and the distribution state of the refractive index are controlled by a technique such as lithography and electron beam drawing is used as a diffractive optical element.

There are many types of diffractive optical elements, but some are known to have polarization dependence by devising the grating pitch or the sectional shape. For example,
A method for manufacturing a polarization-dependent diffractive optical element by ion-exchange of a birefringent material is described in Tech. Digest on 2nd Optoel
ectronics Conf. pp. 166-169 (1988).

[0004]

[Problems to be Solved by the Invention] Tech. Digest on
In the method described in 2nd Optoelectronics Conf. Pp.166-169 (1988), a metal thin film corresponding to the phase pattern of a diffractive optical element is formed on the surface of a LiNbO ₃ substrate by a lithography technique and melted by heating. A polarization dependent diffractive optical element is manufactured by immersing a substrate in an acid and ion-exchange to form a phase grating, and then forming a dielectric for compensating the phase on the phase grating.
In addition to this method, some proposals have been made regarding polarization-dependent diffractive optical elements, but the process is often complicated, and development of a method for manufacturing polarization-dependent diffractive optical elements with high productivity is desired. There is.

An object of the present invention is to solve the above problems and to obtain a method for producing a diffraction-type optical element with high productivity, which is capable of producing a polarization-dependent diffraction-type optical element.

[0006]

The method for producing a diffractive optical element of the present invention is a state in which a polymerizable liquid crystal compound in a liquid crystal state is mixed with a region having a different optical anisotropy from an adjacent region. It is characterized in that a diffractive optical element is produced by polymerizing and hardening in an oriented state.

In a certain liquid crystal state, the polymerizable liquid crystal compound can control the alignment by an external electric energy such as an electric field, a magnetic field, an alignment film, and the like. It is possible to maintain the alignment state in the state.

The functional group of the polymerizable liquid crystal compound may be any group capable of causing a polymerization reaction such as an epoxy group, an acrylate group and a methacrylate group. In particular, the polymerizable liquid crystal having an acrylate group or a methacrylate group does not generate a leaving compound or the like during the polymerization, and is characterized by being photopolymerizable, so that the polymerizable liquid crystal compound is cured in the aligned state. It can be preferably used in the production method of the present invention.

Even if the polymerizable liquid crystal compound does not become a liquid crystal state by itself, if a mixture of several kinds of polymerizable compounds exhibits liquid crystallinity in a certain temperature range, the mixture is used as a polymerizable liquid crystal. It can be used as a compound.

As the polymerization and curing method, a photopolymerization method, a photopolymerization method or the like is used, but a photopolymerization method is preferable. When polymerizing and curing, the polymerizable liquid crystal compound needs to be in a liquid crystal state.

When photopolymerization is used, the characteristic of the polymerizable liquid crystal compound is that the liquid crystal state is at least 10 ° C. and 90 ° C.
It is preferably expressed in the following region, more preferably 15 ° C or higher and 70 ° C or lower. It is preferable that the temperature range in which a liquid crystal is present in any of these temperature regions has a width of 10 ° C. or more, and more preferably 15 ° C. or more. It is preferable in manufacturing that the temperature range of the liquid crystal state is as wide as possible. The phase transition behavior of the liquid crystal may be different in the temperature rising process and the temperature lowering process, but the liquid crystal phase may be expressed in the above temperature range in either process. In addition, it is necessary to be an isotropic state in a temperature range higher than the liquid crystal state. 10 ℃
In the polymerizable liquid crystal compound that takes a liquid crystal state only in the region below, a cooling step is required in production, and the viscosity of the polymerizable liquid crystal tends to increase in the low temperature region to obtain a uniform alignment state. Is often difficult. On the other hand, in the case of a polymerizable liquid crystal compound in which a liquid crystal phase appears only in a temperature range higher than 90 ° C., it is necessary to raise the temperature to higher than 90 ° C. in order to obtain a liquid crystal phase, and thermal polymerization is performed while maintaining this temperature. It may progress and may cause a problem in the process.

When the thermal polymerization is used, the temperature required for the thermal polymerization needs to be within the temperature range in which the polymerizable liquid crystal compound exhibits a liquid crystal state.

The liquid crystal state is not particularly limited, but is preferably a nematic state, a smectic state, more preferably a nematic state. These are often superior to other liquid crystal states in that the controllability of alignment is easy. If it is in a crystalline state or an isotropic state before photo-curing, it is difficult to obtain a controlled fine alignment state as a diffractive optical element after curing. Further, it is possible to use a polymerizable liquid crystal compound that does not maintain the optical anisotropy required as a diffractive optical element because the orientation is largely disturbed after curing even though it has a good alignment state before photocuring. Can not.

In order to obtain the chiral nematic state, it can be obtained by mixing a chiral liquid crystal with a polymerizable liquid crystal having a nematic state. In this case, when the amount of the chiral liquid crystal is 10% by weight or less with respect to the nematic liquid crystal. The chiral liquid crystal, if present, does not necessarily have to be polymerizable.

The chemical formulas of the preferred polymerizable liquid crystal compounds are shown below in (1) to (19). When these are used alone, and when problems such as film-forming properties and optical properties after curing occur, a mixture may be used.

[0016]

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[0017]

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[0018]

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[0019]

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[0020]

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[0021]

[Chemical 6]

[0022]

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[0023]

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[0024]

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[0025]

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[0026]

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[0027]

[Chemical 12]

[0028]

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[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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[0034]

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[0035]

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However, the above (1) to (19)
R ₁ and R ₃ are linear alkyl groups having 8 or less carbon atoms, linear alkoxy groups or none, R ₂ is alkyl groups having 10 or less carbon atoms, alkoxy groups having 10 or less carbon atoms, cyano groups, fluorine, chlorine or hydrogen. Is. In addition, as shown in the chemical formula (20), A indicates an acrylate group or a methacrylate group.

Some of the above compounds are CONFERENCE RECORD OF
THE 1994 INTERNATIONAL DISPLAY RESEARCH CONFERENCE
P161-164, JP-A-62-70406 and the like.

Further, it is preferable to add an initiator to the polymerizable liquid crystal compound having an acrylate group and / or a methacrylate group. When an initiator is added, it may affect the orientation of the polymerizable liquid crystal compound and may affect the phase transition temperature and the like, so it is preferably 3% by weight or less with respect to the polymerizable liquid crystal compound. If the amount of the initiator is too small, the efficiency of the reaction is deteriorated. Therefore, the lower limit of the amount of the initiator is preferably 0.01% by weight or more, more preferably 0.0
5% by weight or more. As the initiator, it is preferable to use an initiator that does not change as much as possible as compared with the case where the orientation of the liquid crystal is not added. In the case of the photoinitiator, any known photoinitiator may be used as long as it can efficiently react at the light wavelength used for curing.

The polymerizable liquid crystal compound before polymerization and curing needs to be in an alignment state in which adjacent regions having different optical anisotropies are mixed, and the optical anisotropy here means the alignment. By different states, for example, Δn · d represented by the product of the birefringence and the film thickness and the direction of the optical axis are different. The diffractive optical element obtained by the manufacturing method of the present invention is a set of minute optical anisotropy, and the magnitude of the optical anisotropy in each minute region and its dispersion state are
It is designed according to the purpose of use as a diffractive optical element.

In a polymerizable liquid crystal compound in a liquid crystal state, a method of forming an alignment state in which adjacent regions having different optical anisotropies are mixed is provided between a pair of conductive substrates finely processed in at least one of them. The polymerizable liquid crystal compound is sandwiched and a voltage is applied, or the polymerizable liquid crystal compound is sandwiched between a pair of substrates having an alignment film in which at least one is finely processed so that the alignment states of adjacent minute regions are different. There is a method of sandwiching, but the former method is preferable.

As a method for providing an alignment state in which regions having different optical anisotropies of adjacent regions are mixed, a polymerizable liquid crystal compound is sandwiched between a pair of conductive substrates, at least one of which is finely processed, and a voltage is applied. In the method by applying, if photopolymerization is used as a method for polymerizing and curing,
Either of the conductive substrates must be polymerized and cured light transmissive. As such a conductive substrate, a known material such as an ITO (indium tin oxide) electrode on glass can be used.

The fine processing referred to here means fine processing for the electrodes on the glass. The pitch of the fine processing needs to be large enough to produce the diffraction effect.
The thickness is preferably from 01 to 100 μm, more preferably from 0.1 to 30 μm. This fine processing can be performed by a known lithography method or the like. Of course, it goes without saying that the diffractive optical element according to the manufacturing method of the present invention does not utilize the diffraction effect of this finely processed conductive substrate. By sandwiching the polymerizable liquid crystal compound using such a substrate and applying a voltage while maintaining an appropriate interval, a difference occurs in the orientation of the polymerizable liquid crystal compound in a portion with an electrode and a portion without the electrode. As a result, a difference occurs in the optical anisotropy of each minute portion, so that the diffraction effect is exhibited. It is a feature of the production method of the present invention that the liquid crystal alignment state in which the diffraction effect is exhibited is polymerized and cured to maintain the diffraction effect.

Here, the substrate interval is 0.05 to 100.
μm is preferable, and more preferably 1 to 50 μm.
m. A well-known micro spacer or the like is preferably used to control the distance between the substrates. Further, in order to better control the alignment of the polymerizable liquid crystal compound, an alignment film may be further provided on the conductive substrate. As the liquid crystal alignment film, a well-known rubbing-treated polyimide film, polyvinyl alcohol, or an oblique vapor deposition film of SiO _x is preferably used as the liquid crystal alignment film. The rubbing direction of the alignment film and the fine processing of the conductive substrate are designed according to the purpose.

As a method of generating minute regions in which adjacent regions have different optical anisotropies, a polymerizable liquid crystal compound is sandwiched between a pair of conductive substrates, at least one of which is finely processed, and a voltage is applied. When the method is used, the polymerizable liquid crystal compound needs to have dielectric anisotropy. Either positive or negative dielectric anisotropy can be used.

The cured product of the polymerizable liquid crystal compound in the state after polymerization and curing serves as a diffractive optical element, but if sufficient strength cannot be obtained, it may be formed on a support. When used as a transmission type diffractive optical element, examples of the support include glass and plastic substrates. A film may be used as the plastic substrate,
Preferable materials are polyester, polyarylate, polycarbonate, polysulfone, polyethersulfone, polyetheretherketone, polyamide, polyimide, aramid, triacetylcellulose and copolymers thereof.

These supports have a measurement wavelength of 400 nm to 80
It is preferable that the transmittance is 80% or more and the haze value is 1% or less in the range of 0 nm. When used as a polarization-dependent diffractive optical element, it is preferable to use a well-known retardation plate, a polarizing plate or an optically isotropic one as a support. The term “optical isotropic” as used herein means a film having a retardation of 20 nm or less when measured with light having a wavelength of 590 nm. A diffractive optical element having various optical characteristics depending on the purpose can be obtained by combining the retardation plate and the polarizing plate.

On the other hand, it is not always necessary to use a light transmission type support as the reflection type diffractive optical element, and a reflection plate may be provided. A metal such as aluminum or stainless steel is preferably used as the material of the reflector. Of course, it is also possible to stack these metals on a transparent substrate such as glass by a sputtering method or the like.

As a method for laminating the cured product on the support, a method of curing the polymerizable liquid crystal compound and then peeling off the cured product from the substrate required for curing and transferring it to the support is preferably used. . When the transfer method is used, it is preferable that the adhesiveness between the substrate used for polymerizing and curing the polymerizable liquid crystal compound and the cured product is weak. Further, if the substrate used in the process of polymerizing and curing is a substrate having the above-mentioned characteristics, it can be directly used as a support without being transferred.

The support may be on both sides of the cured product, and when only one side is provided, a hard coat layer or antireflection layer may be provided on the surface opposite to the support. These can be formed by known materials and manufacturing methods.

[0050]

Example 1 <Fabrication of Diffractive Optical Element> First, the following chemical formulas (21)-
The polymerizable liquid crystal compound represented by (23) was synthesized by the method described below.

[0051]

[Chemical 21]

[0052]

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[0053]

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The polymerizable liquid crystal compound represented by the chemical formula (21) was synthesized as follows. Therefore, first, 4- [4-n-pentylphenylethynyl] phenol represented by the chemical formula (24) was synthesized by a known method.

[0055]

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13.4 g of this compound and 15.6 g of triethylamine were dissolved in 200 ml of tetrahydrofuran, and this solution was cooled to 5 ° C. 50 ml of a tetrahydrofuran solution containing 7.0 g of acrylic acid chloride was added to this.
After dropping over a period of 1 minute, the mixture was reacted for 1 hour. After completion of the reaction, 500 ml of ethyl acetate was added for extraction, and the organic layer was washed with a dilute aqueous solution of sodium hydrogen carbonate and then with water. The organic layer was dried using anhydrous sodium sulfate and then washed with water. After drying the organic layer with anhydrous sodium sulfate, the solvent was distilled off to obtain 17.5 g of a crude product. This crude product was produced by subjecting it to column chromatography. This column treatment was performed using silica gel as a carrier and ethyl acetate: n-hexane = 1: 8 as a developing solvent. Further, it was recrystallized from methanol to obtain 9.5 g of the polymerizable liquid crystal compound represented by the chemical formula (21).

Next, the polymerizable liquid crystal compound represented by the chemical formula (22) was synthesized as follows. Therefore, first, 4-propylcyclohexylphenol represented by the chemical formula (25) was synthesized by a known method.

[0058]

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11.2 g of this compound and 15.6 g of triethylamine were dissolved in 200 ml of tetrahydrofuran, and this solution was cooled to 5 ° C. 50 ml of a tetrahydrofuran solution containing 7.0 g of acrylic acid chloride was added to this.
After dropping over a period of 1 minute, the mixture was reacted for 1 hour. After completion of the reaction, 500 ml of ethyl acetate was added for extraction, and the organic layer was washed with a dilute aqueous solution of sodium hydrogen carbonate and then with water. The organic layer was dried using anhydrous sodium sulfate and then washed with water. After drying the organic layer with anhydrous sodium sulfate, the solvent was distilled off to obtain 14.5 g of a crude product. This crude product was produced by subjecting it to column chromatography. This column treatment was performed using silica gel as a carrier and ethyl acetate: n-hexane = 1: 8 as a developing solvent. Further, it was recrystallized from methanol to obtain 7.8 g of the polymerizable liquid crystal compound represented by the chemical formula (22).

Subsequently, the polymerizable liquid crystal compound represented by the chemical formula (23) was synthesized as follows. Therefore, first, 40 g of 4-hydroxy-4′-cyanobiphenyl and 53 g of triethylamine were dissolved in 400 ml of tetrahydrofuran, and this solution was cooled to 5 ° C. A solution of 25 g of acrylic acid chloride in 200 m of tetrahydrofuran
1 was added dropwise over 15 minutes and then reacted for 1 hour. After completion of the reaction, 1000 ml of ethyl acetate was added for extraction, the organic layer was washed with a dilute aqueous solution of sodium hydrogen carbonate, and then further washed with water. After drying the organic layer with anhydrous sodium sulfate, the solvent was distilled off to obtain 45 g of a crude product. This was subjected to column chromatography (carrier; silica gel, developing solvent; ethyl acetate: n-hexane = 1: 5) and recrystallized from methanol to obtain 20 g of the polymerizable liquid crystal compound represented by the chemical formula (23). .

Thus obtained chemical formulas (21) to (2
The polymerizable liquid crystal compound of 3) is added to 40: 4, respectively.
They were mixed at a ratio of 0:20 (molar ratio). This mixture of polymerizable liquid crystal compounds is in a nematic liquid crystal state at least from around room temperature to 64 ° C, and isotropic at 64 ° C or higher. Further, as the photoinitiator, 2,2-dimethoxy-2-phenylacetophenone commercially available under the trade name "Irgacure 651" manufactured by Ciba-Geigy Co.,
0.5% by weight of the polymerizable liquid crystal compound mixture was mixed to obtain a polymerizable liquid crystal compound mixture which was sandwiched between substrates to be described later.

The distance between the conductive substrates with ITO electrodes is 4 μm.
m, the ITO electrode on one side is a stripe electrode with a pitch of 10 μm, the other ITO electrode is a solid electrode, and a polyimide film is used as an alignment film on both electrodes to form a vertical direction with respect to the longitudinal direction of the stripe electrode. Then, a glass cell having a size of 4 cm × 4 cm which was rubbed so as to be anti-parallel was prepared. Glass thickness is 1.1 mm
Was used.

The above-mentioned polymerizable liquid crystal compound mixture was poured into this cell at 70 ° C., and after cooling to 25 ° C., 5 V was applied between the electrodes for 5 V.
A voltage of 0 Hz was applied. When observed under a polarizing microscope in this state, it was confirmed that the polymerizable liquid crystal compound mixture had an alignment state in which adjacent regions having different optical anisotropies were mixed. And then
Ultraviolet irradiation was performed at ² mW / cm ^{2 for} 3 minutes. Furthermore, after irradiation with ultraviolet rays, aging was performed at 150 ° C. for 1 hour.

Thus, the diffractive optical element having the structure shown in FIG. 1 was obtained. FIG. 1 schematically shows an alignment state of a polymerizable liquid crystal compound in a state where a polymerizable liquid crystal mixture is injected into a glass cell and an electric field is applied in the film thickness direction. 1A is a cross-sectional view of the diffractive optical element, and FIG.
Is a plan view thereof. In the figure, 1 is a glass substrate, 2 is a striped ITO electrode, 3 is a solid ITO electrode, 4 and 5 are alignment films, 6 is a polymerizable liquid crystal compound, 7 is a rubbing direction of the alignment film, and 8 is an electric field direction. is there.

<Evaluation of Diffractive Optical Element> Light from a halogen lamp is converted into parallel rays by a lens and an aperture,
The light having a spot diameter of 4 mm and converted into parallel rays was used as the incident light, and the correlation between the incident polarization state, the emission polarization state, and the diffraction state was evaluated. This incident light is in a substantially non-polarized light state, and the polarization state of the incident light is controlled by using a polarizing plate.

FIG. 2 schematically shows an arrangement for evaluating the present diffractive optical element. In FIG. 2, 10 is a diffractive optical element, 11 is an alignment film rubbing direction, 12 is a blank sheet, 13 is incident light, 14 is outgoing diffracted light, and 15 is a projection state of diffracted light. As shown in FIG. 2, when non-polarized light was incident, it was observed that the emitted light was spotted in a direction parallel to the rubbing direction, and it was confirmed that light was diffracted.

Further, in order to evaluate the correlation between the incident polarization state, the emission polarization state, and the diffraction state, a linear polarizing plate was inserted on the entrance side and the exit side as necessary for the evaluation. That is, in the configuration of FIG. 2, a linear polarizing plate was inserted between the present optical element and the light source, and between the present optical element and a blank sheet, and the angle of the linear polarizing plate was adjusted for evaluation.
The state of the emitted light was observed by projecting it on a white paper, which was about 20 cm away from the sample.

As a result, when the rubbing direction of the optical element and the polarization axes of the two polarizing plates are parallel to each other, it is observed that the emitted light is spotted on a white paper, and the light is diffracted. Was confirmed. Further, when the rubbing direction of the optical element and the polarization axis of one polarizing plate were parallel to each other and the polarization axis of the other polarizing plate was perpendicular to each other, no light was transmitted and no outgoing light was observed. Furthermore, when the polarization axes of the two polarizing plates are parallel and perpendicular to the rubbing direction of the optical element, the emitted light is only observed on the extension of the incident light optical axis,
It was confirmed that diffraction did not occur.

A polarizing plate is not inserted between the optical element and the light source, but a linear polarizing plate is inserted only between the optical element of this type and a blank sheet, and the angle of the linear polarizing plate is adjusted. It evaluated similarly. As a result, when the rubbing direction of the optical element and the polarization axis of the polarizing plate were parallel, it was observed that the emitted light was spotted on a white paper, and it was confirmed that the light was diffracted. However, in this case, the brightness of the spot appearing on the extension of the optical axis of the incident light was weak. It was also confirmed that when the rubbing direction of the optical element and the polarization axis of the polarizing plate were at right angles, only the emitted light was observed on the extension of the incident light optical axis, and no diffraction occurred.

The above results are for the diffractive optical element after aging, but almost the same results are obtained although the voltage application state before ultraviolet curing and the diffracted light intensity and the like are slightly different after ultraviolet curing. It was Further, the glass substrate having the conductive film was peeled off and the same evaluation was performed, but the result was the same as the above. Thus, it was shown that the diffractive optical element manufactured by the manufacturing method of the present invention has polarization dependency.

[0071]

Example 2 <Fabrication of Diffractive Optical Element> A conductive substrate with ITO electrodes has a space of 8 μm, ITO electrodes on both sides are stripe electrodes having a pitch of 10 μm, and is orthogonal, and a polyvinyl alcohol film is used as an alignment film. After forming on both electrodes,
4 cm x 4 rubbed so as to be antiparallel in the direction perpendicular to the longitudinal direction of the striped electrode on one side
A glass cell having a size of cm was prepared. The glass used had a thickness of 1.1 mm.

The same polymerizable liquid crystal compound mixture as in Example 1 was injected into this cell at 70 ° C., cooled to 25 ° C., and a voltage of 9 V and 50 Hz was applied between the electrodes. When observed under a polarization microscope in this state, it was confirmed that the polymerizable liquid crystal compound was in an aligned state in which adjacent regions having different optical anisotropies were mixed. Then, after that, ultraviolet irradiation was performed at ² mW / cm ^{2 for} 3 minutes.
Furthermore, after irradiation with ultraviolet rays, aging was performed at 150 ° C. for 1 hour.

Thus, a diffractive optical element as schematically shown in FIG. 3 was produced. Note that the alignment film is omitted in FIG. In FIG. 3, 20 is a glass substrate, 21 is a striped ITO electrode, and 22 is a polymerizable liquid crystal compound.

<Evaluation of Diffractive Optical Element> Light from a halogen lamp is converted into parallel rays by a lens and an aperture,
Approximately 20c from the sample when non-polarized light is incident, with incident light being parallel light with a spot diameter of 4 mm
FIG. 4 schematically shows a state of emitted light projected on a white paper located at a distance of m. In FIG. 4, 30 is a blank sheet and 31 is a spot generated by the emitted light.

As a result, it was confirmed that diffraction had occurred. Further, although the voltage applied state before the UV curing and the diffracted light intensity and the like after the UV curing were slightly different, almost the same result was obtained. Furthermore, the conductive substrate was peeled off and the same evaluation was performed, but the evaluation results were the same.

[0076]

INDUSTRIAL APPLICABILITY The present invention is a novel diffraction type compound in which a polymerizable liquid crystal compound in a liquid crystal state is formed with a large number of minute regions having mutually different optical anisotropies, and then polymerized and cured in that state. The present invention relates to a method for manufacturing an optical element, and the present invention has an effect that a diffractive optical element having highly functional optical characteristics, which is suitably used for optical communication, a display device, and the like, can be provided with high productivity.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a diffractive optical element in Example 1.

FIG. 2 Arrangement of diffractive optical element evaluation

FIG. 3 is a schematic diagram of a diffractive optical element in Example 2.

FIG. 4 is an emitted light projected on a white paper in Example 2.

[Explanation of symbols]

 1 Glass substrate 2 Striped ITO electrode 3 Solid ITO electrode 4 Alignment film 5 Alignment film 6 Polymerizable liquid crystal compound 7 Alignment film rubbing direction 8 Electric field direction 10 Diffractive optical element 11 Alignment film rubbing direction 12 White paper 13 Incident light 14 Outgoing light 15 Projected outgoing light 20 Glass substrate 21 Striped ITO electrode 22 Polymerizable liquid crystal compound 30 White paper 31 Spot generated by outgoing light

Claims (4)

[Claims] 1. A diffractive optical element is manufactured by polymerizing and curing a polymerizable liquid crystal compound in a liquid crystal state in an alignment state in which regions having different optical anisotropies from adjacent regions are mixed. A method of manufacturing a diffractive optical element, comprising: 2. A polymerizable liquid crystal compound is sandwiched between a pair of conductive substrates, at least one of which is finely processed to have an alignment state in which regions having different optical anisotropies from adjacent regions are mixed. The method of manufacturing a diffractive optical element according to claim 1, wherein the method is obtained by applying a voltage. 3. The method for producing a diffractive optical element according to claim 1, wherein a polymerizable liquid crystal compound having an acrylate group and / or a methacrylate group is used as the polymerizable liquid crystal compound. 4. The method for producing a diffractive optical element according to claim 1, wherein the means for polymerizing and curing is photopolymerization.